Chiang Mai yesterday received the most undesirable accolade of becoming the most polluted city on the planet.
The grim news from the IQ AirVisual air monitoring website came as authorities revealed that the situation had caused 30,000 people to go to hospital because of respiratory illnesses over the last three months.
The Chiang Mai provincial public health office said 31,788 patients suffering from air pollution-related illnesses from January to March 5 this year, said Dr Suwanchai Wattanayingcharoen, director-general of the Department of Health under the Public Health ministry.
Chiang Mai's air quality has been ranked one of the planet's three worst cities for pollution since the start of March.
Then, IQ AirVisual yesterday announced that the city had in fact been the very worst place in the world for many straight days with a USAQI of 195, followed by Beijing on 182.
USAQI is an Air Quality Index used by the United States Environmental Protection Agency (US EPA).
Yesterday morning, the level of PM2.5 in Chiang Mai rose above 200 microgrammes per cubic metre (µg/m3), according to IQ AirVisual and the Thailand Pollution Control Department (PCD)'s air monitoring station gave similar findings.
At noon yesterday, the level of PM2.5 recorded at Chang Puek Road in Muang district rose to almost 200 µg/m3.
The Thailand Meteorological Department yesterday warned the air pollution would last for another week.
That is because the southern west wind current would be too weak to blow away the dust particles and these were trapped by the cool weather in the evenings.
The main contributor to the deteriorating situation in the North is said to be the considerable heat from wildfires caused by open burning in Myanmar forests and locally.
The northern region yesterday had 910 hotspots -- 617 in protected areas, 293 in forests and 16 in individual farm plots. Mae Hong Son had the most hotspots at 442, followed by Chiang Mai at 211 and Tak 108.
Wildfires and haze in the upper North have started to impact people's health in six provinces: Chiang Rai, Chiang Mai, Lampang, Mae Hong Son, Tak and Phayao.
Deputy commander of the Third Army Area, Maj Gen Thanadpol Kosaisewee, said 60 patrol officers have been dispatched to five districts in Chiang Mai until tomorrow.